<template>
	<div>
		<router-link tag='div' to='/' class="header-abs" v-show="showAbs">
			<div class="iconfont header-abs-back" >&#xe624;</div>
		</router-link>
		<div class="header-fixed"
			 v-show="!showAbs"
			 :style="opacityStyle">
			<router-link to='/'>
				<div class="iconfont header-fixed-back" >&#xe624;</div>
			</router-link>
			景点详情
		</div>
	</div>
</template>

<script>
	export default {
		name:'DetailHeader',
		data () {
			return {
				showAbs: true,
				opacityStyle: {
					opacity:0
				}
			}
		},
		methods: {
			handleScroll(){
				const top = document.documentElement.scrollTop
				if(top > 80 ) {
					let opacity = top / 163
					opacity = opacity > 1 ? 1:opacity
					this.opacityStyle = {opacity}
					this.showAbs = false
				}else {
					this.showAbs = true
				}
			}			
		},
		activated () {
			window.addEventListener('scroll',this.handleScroll)
		},
		deactivated () {  //页面即将隐藏时执行
			window.removeEventListener('scroll',this.handleScroll)
		}
	}
</script>

<style lang="stylus" scoped>
	@import '~styles/varibles.style'
	.header-abs
		position:absolute
		left:.2rem
		top:.2rem
		width:.8rem
		height:.8rem
		line-height:.8rem
		text-align:center	
		border-radius:.4rem
		background: rgba(0,0,0,.8)
		.header-abs-back
			color:#fff
			font-size:.4rem
	.header-fixed
		z-index:2
		position:fixed
		top:0
		left:0
		right:0
		overflow:hidden
		height:$headerHeight
		line-height:$headerHeight
		text-align:center
		color:#fff
		background: $bgColor
		font-size:.35rem
		.header-fixed-back
			position:absolute
			top:0
			height:0
			width:.64rem
			text-align:center
			font-size:.4rem
			color:#fff
</style>